Planchet



July 14, 1964 BRQIDA 3,140,796

PLANCHET Filed Aug. 22, 1962 F|G 3 I 1 23 r 36 i 2 FIG 2 7 5 is I [f I xI I W I IN VEN TOR IflN/A-Z Eff/F4 i7?" rmers,

United States Patent 3,140,796 PLANCHET Daniel Broida, Ladue, M0.,assignor to Sigma Chemical Company, a corporation of Missouri Filed Aug.22, 1962, Ser. No. 218,615 2 Claims. (Cl. 220-66) This invention relatesto planchets, particularly for use for radioassays.

Planchets for radioassays are of two main varieties, fiat and cupped.The cupped type has a bottom surrounded by a circumferential rim. Thisinvention is more particularly directed to the cupped type.Commercially, the cupped planchets are available in smoothbottomed andconcentric ring bottomed types. The bottom surface of the latter type isembossed to form, on the inner side, a series of concentric radiallyspaced annular ridges. This provides, in effect, a plurality of radiallyspaced shallow annular troughs, each bounded by uninterrupted dikes, sothat materials, particularly liquids, which are placed in the planchet,are inhibited from creeping radially across the bottom.

One of the objects of this invention is to provide a planchet in whichuniform distribution of materials is encouraged.

Another object is to provide planchets of the concentric ring bottomtype in which uniform circumferential distribution is encouraged.

Still other objects will become apparent to those skilled in the art inthe light of the following description and accompanying drawing.

In accordance with this invention, generally stated, a planchet isprovided, with a plurality of concentric, annularly raised ridges in itsbottom, and with a plurality of radially extending, symmetricallyarranged ribs, lower in profile than the annularly extending ridges.

The radially extending ribs serve, in addition to making the bottom morerigid, to promote the uniform distribution of materials, around thebottom of the planchet. To this end, the disparity in height between theannular ridges and the radial ribs is significant. If the radial ribswere as high as the annular ridges, there would be danger of segregatingmaterial in one of the areas defined between two successive ribs.

In the drawing, FIGURE 1 is a top plan view of one embodiment ofplanchet of this invention;

FIGURE 2 is a much enlarged sectional view taken along the line 22 ofFIGURE 1; and

FIGURE 3 is a top plan view of another embodiment of planchet of thisinvention.

Referring now to FIGURES 1 and 2 of the drawing for one illustrativeembodiment of this invention, reference numeral 1 indicates a completedplanchet. The planchet 1 has a flat bottom 2, upstanding circumferentialrim 3, four concentric annular ridges 4, 5, 6 and 7, in order from thecenter, and four radially extending, symmetrically arranged ribs 8, 9,and 11.

The annular ridge 4 defines within its compass a flatbottomed basin 14,and with the ridge 5, an annular flatbottomed channel 15. The ridge 5,defines with the ridge 6, an annular flat-bottomed channel 16. Theridges 6 and 7 define between them an annular flat-bottomed channel 17,and the ridge 7 and the rim 3 define between them an outer annularchannel 18.

It can be seen that, in the embodiment shown, the basin 14 and the outerannular channel 18 are uninterrupted by the ribs 8-11. It can also beseen, particularly in FIGURE 2, that the ribs 8-11 are shallower thanthe ridges 47. The small area of the basin 14 makes distribution of thematerial within it of less importance that its distribution through thechannels 15- 3,140,796 Patented July 14, 1964 17 and the absence of theribs within the basin avoids channeling into one quadrant of materialintroduced to the basin. As has been explained heretofore, theshallowness of the radially extending ribs, as compared with the annularridges, permits material to be distributed throughout a channel, beforethe material overflows to the next outer channel. At the same time, ifthe level of the material decreases, as with the evaporation of liquidor sublimation of solids, the amount of material dammed by and betweenthe radial ribs, will remain thus distributed throughout the channel.

Preferably material is introduced into the basin 14, and spillsoutwardly into successively radially outer channels. The outermostchannel 18 is chiefly an overflow channel, in which excess material iscontained. If the planchet is tilted, so as to introduce to theoutermost channel an excess of material, the absence of radial ribspermits material to flow promptly to the low spot and thus be returnedto the next outermost channel 17.

In the embodiment shown in FIGURE 3, a planchet 26 is illustrated, whichhas a bottom 22, a circumferential rim 23, only two annular ridges, aninner ridge 24 and an outer ridge 25 concentric therewith, and sixradial ribs 26, 27, 28, 29, 30 and 31.

The inner ridge 24 defines a central basin 34. In this embodiment, theouter ridge 25 is positioned in relation to the rim 23 in about the sameway as the ridge 7 is positioned with respect to the rim 3 of theembodiment shown in FIGURES 1 and 2. This leaves a wide intermediatechannel 35, traversed by the ribs 26-31, and a relatively narrow channel36 between the ridge 25 and the rim 23. In this embodiment, as in thefirst embodiment shown and described, the bottoms are flat.

In both embodiments, the ridges are radially narrow as compared with thecommercial concentric-ringed planchets known heretofore, leaving wide-rchannels, the bottoms of which are flat, as distinguished from therelatively narrow channels which are apparently somewhat concave incross section in the present crommercial planchets of others. Thisfeature of the present invention also aids the uniform distribution ofmaterial at a uniform depth.

The planchets of this invention can be made of any desired materials,such as aluminum, glass, plastic, stainless steel, iron, copper, or thelike. The metal planchets may be plated. They are normally designed forthrowaway use, but they need not be discarded. They may be made in anydesired size, the present commercial planchets being commonly between 1and 2 inches in diameter. A typical planchet of this invention would be1 7 inches in diameter, with a rim inch high, ridges .015 inch high, andribs .006 inch high. The ridges are approximately inch thick, radially,at their inside roots, the channels about & inch wide radially betweenroots of successive ridges and the basin about inch in diameter. It isto be understood that these specific dimensions are merely illustrative.

Numerous variations, within the scope of the appended claims, will occurto those skilled in the art in the light of the foregoing disclosure.For example, more or fewer ridges and ribs may be employed, and absolutedimensions may be varied, as long as the rim is at least as high as theridges and the ribs are shallower than the ridges.

Having thus described the invention, what is claimed and desired to besecured by Letters Patent is:

1. In a cupped planchet the improvement comprising a flat bottom havinga plurality of concentric annular ridges on its inner surface, and aplurality of radially extending symmetrically positioned ribs on itsinner surface, said ribs being of a height less than the height of saidannular ridges.

2. In a cupped planchet the improvement comprising a flat bottom havinga plurality of concentric annular ridges in its inner surface, theinnermost of said ridges defining a central basin in said bottom and theoutermost of said ridges defining, with a circumferential rim, anannular outer channel, and a plurality of radially extending,symmetrically positioned ribs on the inner surface of the bottom, saidribs extending between the radially outer side of the innermost ridgeand the radially inner side of the outermost ridge, whereby the basinand outer channel are uninterrupted by said ribs, and said ribs being ofa height less than the height of said annular ridges.

References Cited in the file of this patent UNITED STATES PATENTS1,865,742 Chapman July 5, 1932 10 1,970,151 Smith Aug. 14, 19342,080,125 Frost May 11, 1937

2. IN A CUPPED PLANCHET THE IMPROVEMENT COMPRISING A FLAT BOTTOM HAVINGA PLURALITY OF CONCENTRIC ANNULAR RIDGES IN ITS INNER SURFACE, THEINNERMOST OF SAID RIDGES DEFINING A CENTRAL BASIN IN SAID BOTTOM AND THEOUTERMOST OF SAID RIDGES DEFINING, WITH A CIRCUMFERENTIAL RIM, ANANNULAR OUTER CHANNEL, AND A PLURALITY OF RADIALLY EXTENDING,SYMMETRICALLY POSITIONED RIBS ON THE INNER SURFACE OF THE BOTTOM, SAIDRIBS EXTENDING BETWEEN THE RADIALLY OUTER SIDE OF THE INNERMOST RIDGEAND THE RADIALLY INNER SIDE OF THE OUTERMOST RIDGE, WHEREBY THE BASINAND OUTER CHANNEL ARE UNINTERRUPTED BY SAID RIBS, AND SAID RIBS BEING OFA HEIGHT LESS THAN THE HEIGHT OF SAID ANNULAR RIDGES.